Method of determining the acceleration of a turbine in an automatic transmission

ABSTRACT

A method wherein a controller is programmed to determine the acceleration of the turbine in the torque converter to control transmission operation during a shift or gear change by counting the number of teeth during a predetermined cycle and dividing that tooth count by the actual time elapsed between the first and last tooth in an automatic transmission.

BACKGROUND OF THE INVENTION

1. Field Of The Invention

The present invention relates to an automatic transmission primarilyintended for motor vehicle use, and more particularly, to a method ofdetermining the acceleration of a turbine in a torque converter of atransmission that is controlled electronically and hydraulically.

2. Description Of Related Art

Generally speaking, land vehicles require three basic components. Thesecomponents comprise a power plant (such as an internal combustionengine) a power train and wheels. The internal combustion engineproduces force by the conversion of the chemical energy in a liquid fuelinto the mechanical energy of motion (kinetic energy). The function ofthe power train is to transmit this resultant force to the wheels toprovide movement of the vehicle.

The power train's main component is typically referred to as the"transmission". Engine torque and speed are converted in thetransmission in accordance with the tractive-power demand of thevehicle. The vehicle's transmission is also capable of controlling thedirection of rotation being applied to the wheels, so that the vehiclemay be driven both forward and backward.

A conventional transmission includes a hydrodynamic torque converter totransfer engine torque from the engine crankshaft to a rotatable inputmember of the transmission through fluid-flow forces. The transmissionalso includes frictional units which couple the rotating input member toone or more members of a planetary gearset. Other frictional units,typically referred to as brakes, hold members of the planetary gearsetstationary during flow of power. These frictional units are usuallybrake clutch assemblies or band brakes. The drive clutch assemblies cancouple the rotating input member of the transmission to the desiredelements of the planetary gearsets, while the brakes hold elements ofthese gearsets stationary. Such transmission systems also typicallyprovide for one or more planetary gearsets in order to provide variousratios of torque and to ensure that the available torque and therespective tractive power demand are matched to each other.

Transmissions are generally referred to as manually actuated orautomatic transmission. Manual transmission generally include mechanicalmechanisms for coupling rotating gears to produce different ratiooutputs to the drive wheels.

Automatic transmissions are designed to take automatic control of thefrictional units, gear ratio selection and gear shifting. A thoroughdescription of general automatic transmission design principals may befound in "Fundamentals of Automatic Transmissions and Transaxles,"Chrysler Corporation Training Manual No. TM-508A. Additionaldescriptions of automatic transmissions may be found in U.S. Pat. No.3,631,744, entitled "Hydromatic Transmission," issued Jan. 4, 1972 toBlomquist, et al., and U.S. Pat. No. 4,289,048, entitled "Lock-up Systemfor Torque Converter," issued on Sept. 15, 1981 to Mikel, et al. Each ofthese patents is hereby incorporated by reference.

In general, the major components featured in such an automatictransmission are: a torque converter as above-mentioned; fluidpressure-operated multi-plate drive or brake clutches and/or brake bandswhich are connected to the individual elements of the planetary gearsetsin order to perform gear shifts without interrupting the tractive power;one-way clutches in conjunction with the frictional units foroptimization of power shifts; and transmission controls such as valvesfor applying and releasing elements to shift the gears (instant ofshifting), for enabling power shifting, and for choosing the proper gear(shift point control), dependent on shift-program selection by thedriver (selector lever), accelerator position, the engine condition andvehicle speed.

The control system of the automatic transmission is typicallyhydraulically operated through the use of several valves to direct andregulate the supply of pressure. This hydraulic pressure control willcause either the actuation or deactuation of the respective frictionalunits for effecting gear changes in the transmission. The valves used inthe hydraulic control circuit typically comprise spring-biased spoolvalves, spring-biased accumulators and ball check valves. Since many ofthese valves rely upon springs to provide a predetermined amount offorce, it will be appreciated that each transmission design represents afinely tuned arrangement of interdependent valve components. While thistype of transmission control system has worked well over the years, itdoes have its limitations. For example, such hydraulically controlledtransmissions are generally limited to one or a very small number ofengines and vehicle designs. Therefore, considerable cost is incurred byan automobile manufacturer to design, test, build, inventory and repairseveral different transmission units in order to provide an acceptablebroad model line for consumers.

Additionally, it should be appreciated that such hydraulicallycontrolled transmission systems cannot readily adjust themselves in thefield to compensate for varying conditions such as normal wear on thecomponents, temperature swings and changes in engine performance overtime. While each transmission is designed to operate most efficientlywithin certain specific tolerances, typical hydraulic control systemsare incapable of taking self-corrective action on their own to maintainoperation of the transmission at peak efficiency.

However, in recent years, a more advanced form of transmission controlsystem has been proposed, which would offer the possibility of enablingthe transmission to adapt itself to changing conditions. In this regard,Leising, et al. U.S. Pat. No. 3,956,947, issued on May 18, 1976, whichis hereby incorporated by reference, sets forth a fundamentaldevelopment in this field. Specifically, this patent discloses anautomatic transmission design which features an "adaptive" controlsystem that includes electrically operated solenoid-actuated valves forcontrolling certain fluid pressures. In accordance with thiselectric/hydraulic control system, the automatic transmission would be"responsive" to an acceleration factor for controlling the output torqueof the transmission during a shift from one ratio of rotation (betweenthe input and output shafts of the transmission) to another.Specifically, the operation of the solenoid-actuated valves would causea rotational speed versus time curve of a sensed rotational component ofthe transmission to substantially follow along a predetermined pathduring shifting.

3. Objects Of The Present Invention

It is one of the principal objects of the present invention to provide asignificantly advanced electronically controlled transmission which isfully adaptive. By fully adaptive, it is meant that substantially allshifts are made using closed-loop control (i.e., control based onfeedback). In particular, the control is closed loop on speed, speedratio, or slip speed of either N_(t) (turbine) of the torque converterand N_(e) (engine) or a combination of N_(t) and N_(o) (output) whichwill provide the speed ratio or slip speed. This transmission control isalso capable of "learning" from past experience and making appropriateadjustments on that basis.

Another object of the present invention is to provide an automatictransmission in which the shift quality is maintained approximatelyuniform regardless of the engine size, within engine performancevariations or component conditions (i.e. the transmission control systemwill adapt to changes in engine performance or in the condition of thevarious frictional units of the transmission).

It is a more specific object of the present invention to provide amethod of determining the acceleration of a turbine in a torqueconverter of an automatic transmission to control transmission operationduring a shift or gear change.

This application is one of several applications filed on the same date,all commonly assigned and having similar Specification and Drawings,these applications being identified below.

    __________________________________________________________________________    U.S. Ser. No.                                                                        U.S. Pat. No.                                                                        Title                                                           __________________________________________________________________________    187,772                                                                              4,875,391                                                                            AN ELECTRONICALLY-CONTROLLED,                                                 ADAPTIVE AUTOMATIC TRANSMISSION                                               SYSTEM                                                          187,751       AUTOMATIC FOUR-SPEED TRANSMISSION                               189,493                                                                              4,915,204                                                                            PUSH/PULL CLUTCH APPLY PISTON OF AN                                           AUTOMATIC TRANSMISSION                                          187,781       SHARED REACTION PLATES BETWEEN                                                CLUTCH ASSEMBLIES IN AN AUTOMATIC                                             TRANSMISSION                                                    189,492       CLUTCH REACTION AND PRESSURE PLATES                                           IN AN AUTOMATIC TRANSMISSION                                    188,602       BLEEDER BALL CHECK VALVES IN AN                                               AUTOMATIC TRANSMISSION                                          188,610       PRESSURE BALANCED PISTONS IN AN                                               AUTOMATIC TRANSMISSION                                          189,494       DOUBLE-ACTING SPRING IN AN                                                    AUTOMATIC TRANSMISSION                                          188,613                                                                              4,907,681                                                                            PARK LOCKING MECHANISM FOR AN                                                 AUTOMATIC TRANSMISSION                                          187,770                                                                              4,887,491                                                                            SOLENOID-ACTUATED VALVE ARRANGEMENT                                           OF AN AUTOMATIC TRANSMISSION SYSTEM                             188,796       RECIPROCATING VALVES IN A FLUID                                               OF AN AUTOMATIC TRANSMISSION                                    187,705                                                                              4,887,512                                                                            VENT RESERVOIR IN A FLUID SYSTEM OF                                           AN AUTOMATIC TRANSMISSION                                       188,592       FLUID ACTUATED SWITCH VALVE IN AN                                             AUTOMATIC TRANSMISSION                                          188,598                                                                              4,893,652                                                                            DIRECT-ACTING, NON-CLOSE CLEARANCE                                            SOLENOID-ACTUATED VALVES                                        188,618       NOISE CONTROL DEVICE FOR A                                                    SOLENOID-ACTUATED VALVE                                         188,605                                                                              4,871,887                                                                            FLUID ACTUATED PRESSURE SWITCH FOR                                            AN AUTOMATIC TRANSMISSION                                       187,210       METHOD OF APPLYING REVERSE GEAR OF                                            AN AUTOMATIC TRANSMISSION                                       187,672       TORQUE CONVERTER CONTROL VALVE IN A                                           FLUID SYSTEM OF AN AUTOMATIC                                                  TRANSMISSION                                                    187,120       CAM-CONTROLLED MANUAL VALVE IN AN                                             AUTOMATIC TRANSMISSION                                          187,181                                                                              4,907,475                                                                            FLUID SWITCHING MANUALLY BETWEEN                                              VALVES IN AN AUTOMATIC TRANSMISSION                             187,704       METHOD OF OPERATING AN ELECTRONIC                                             AUTOMATIC TRANSMISSION SYSTEM                                   188,020       METHOD OF SHIFT SELECTION IN AN                                               ELECTRONIC AUTOMATIC TRANSMISSION                                             SYSTEM                                                          187,991       METHOD OF UNIVERSALLY ORGANIZING                                              SHIFTS FOR AN ELECTRONIC AUTOMATIC                                            TRANSMISSION SYSTEM                                             188,603       METHOD OF DETERMINING AND                                                     CONTROLLING THE LOCK-UP OF A TORQUE                                           CONVERTER IN AN ELECTRONIC                                                    AUTOMATIC TRANSMISSION SYSTEM                                   188,617       METHOD OF ADAPTIVELY IDLING AN                                                ELECTRONIC AUTOMATIC TRANSMISSION                                             SYSTEM                                                          189,553       METHOD OF DETERMINING THE DRIVER                                              SELECTED OPERATING MODE OF AN                                                 AUTOMATIC TRANSMISSION SYSTEM                                   188,615       METHOD OF DETERMINING THE SHIFT                                               LEVER POSITION OF AN ELECTRONIC                                               AUTOMATIC TRANSMISSION SYSTEM                                   187,771       METHOD OF DETERMINING THE FLUID                                               TEMPERATURE OF AN ELECTRONIC                                                  AUTOMATIC TRANSMISSION SYSTEM                                   188,607       METHOD OF DETERMINING THE                                                     CONTINUITY OF SOLENOIDS IN AN                                                 ELECTRONIC AUTOMATIC TRANSMISSION                                             SYSTEM                                                          189,579       METHOD OF DETERMINING THE THROTTLE                                            ANGLE POSITION FOR AN ELECTRONIC                                              AUTOMATIC TRANSMISSION SYSTEM                                   188,604                                                                              4,905,545                                                                            METHOD OF CONTROLLING THE SPEED                                               CHANGE OF A KICKDOWN SHIFT FOR AN                                             ELECTRONIC AUTOMATIC TRANSMISSION                                             SYSTEM                                                          188,591       METHOD OF CONTROLLING THE APPLY                                               ELEMENT DURING A KICKDOWN SHIFT FOR                                           ELECTRONIC AUTOMATIC TRANSMISSION                                             SYSTEM                                                          188,608       METHOD OF CALCULATING TORQUE FOR AN                                           ELECTRONIC AUTOMATIC TRANSMISSION                                             SYSTEM                                                          187,150       METHOD OF LEARNING FOR ADAPTIVELY                                             CONTROLLING AN ELECTRONIC AUTOMATIC                                           TRANSMISSION SYSTEM                                             188,595       METHOD OF ACCUMULATOR CONTROL FOR A                                           FRICTION ELEMENT IN AN ELECTRONIC                                             AUTOMATIC TRANSMISSION SYSTEM                                   188,599       METHOD OF ADAPTIVELY SCHEDULING A                                             SHIFT FOR AN ELECTRONIC AUTOMATIC                                             TRANSMISSION SYSTEM                                             188,601       METHOD OF SHIFT CONTROL DURING A                                              COASTDOWN SHIFT FOR AN ELECTRONIC                                             AUTOMATIC TRANSMISSION SYSTEM                                   188,620       METHOD OF TORQUE PHASE SHIFT                                                  CONTROL FOR AN ELECTRONIC AUTOMATIC                                           TRANSMISSION                                                    188,596       METHOD OF DIAGNOSTIC PROTECTION FOR                                           AN ELECTRONIC AUTOMATIC                                                       TRANSMISSION SYSTEM                                             188,597       METHOD OF STALL TORQUE MANAGEMENT                                             FOR AN ELECTRONIC AUTOMATIC                                                   TRANSMISSION SYSTEM                                             188,606       METHOD OF SHIFT TORQUE MANAGEMENT                                             FOR AN ELECTRONIC AUTOMATIC                                                   TRANSMISSION SYSTEM                                             188,616       ELECTRONIC CONTROLLER FOR AN                                                  AUTOMATIC TRANSMISSION                                          188,600       DUAL REGULATOR FOR REDUCING SYSTEM                                            CURRENT DURING AT LEAST ONE MODE OF                                           OPERATION                                                       188,619       UTILIZATION OF A RESET OUTPUT OF A                                            REGULATOR AS A SYSTEM LOW-VOLTAGE                                             INHIBIT                                                         188,593       THE USE OF DIODES IN AN INPUT                                                 CIRCUIT TO TAKE ADVANTAGE OF AN                                               ACTIVE PULL-DOWN NETWORK PROVIDED                                             IN A DUAL REGULATOR                                             188,609       SHUTDOWN RELAY DRIVER CIRCUIT                                   188,614       CIRCUIT FOR DETERMINING THE CRANK                                             POSITION OF AN IGNITION SWITCH BY                                             SENSING THE VOLTAGE ACROSS THE                                                STARTER RELAY CONTROL AND HOLDING                                             AN ELECTRONIC DEVICE IN A RESET                                               CONDITION IN RESPONSE THERETO                                   188,612                                                                              4,901,561                                                                            THROTTLE POSITION SENSOR DATA                                                 SHARED BETWEEN CONTROLLER WITH                                                DISSIMILAR GROUNDS                                              188,611       NEUTRAL START SWITCH TO SENSE SHIFT                                           LEVER POSITION                                                  188,981       OPEN LOOP CONTROL OF SOLENOID COIL                                            DRIVER                                                          __________________________________________________________________________      "Commonly assigned application Ser. No. 07/187,772, filed Apr. 28, 1988     now U.S. Pat. No. 4,875,391 has been printed in its entirety. The Figures     and the entire Specification of that application are specifically     incorporated by reference. For a description of the above copending     applications, reference is made to the above mentioned U.S. Pat. No.     4,875,391."

SUMMARY OF THE INVENTION

To achieve foregoing objects, the present invention provides acomprehensive four-speed automatic transmission system. While thistransmission system particularly features a fully adaptive electroniccontrol system, numerous other important advances are incorporated intothis unique transmission system, as will be described below in detail.

The transmission control system includes a microcomputer-basedcontroller which receives input signals indicative of engine speed,turbine speed, output speed (vehicle speed), throttle angle position,brake applications, predetermined hydraulic pressure, the driverselected gear or operating condition (PRNODDL), engine coolanttemperature, and/or ambient temperature. This controller generatescommand or control signals for causing the actuation of a plurality ofsolenoid-actuated valves which regulate the application and release ofpressure to and from the frictional units of the transmission system.Accordingly, the controller will execute predetermined shift schedulesstored in the memory of the controller through appropriate commandsignals to the solenoid-actuated valves and the feedback which isprovided by various inputs signals.

Another primary feature of the present invention is to provide anadaptive system based on closed-loop control. In other words, theadaptive control system performs its functions based on real-timefeedback sensor information, i.e., the system takes an action whichaffects the output, reads the effect, and adjusts the actioncontinuously in real-time. This is particularly advantageous because thecontrol actuations can be corrected as opposed to an open loop controlin which signals to various elements are processed in accordance with apredetermined program.

In accordance with one aspect of the present invention, the controlleris programmed to determine the acceleration of the turbine in the torqueconverter to control transmission operation during a shift or gearchange by counting the number of teeth during a predetermined cycle anddividing that tooth count by the actual time elapsed between the firstand last tooth.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects, features and advantages of the present invention willbecome more fully apparent from the following detailed description ofthe preferred embodiment, the appended claims and in the accompanyingdrawings in which:

FIG. 12 is a flow chart of the overall operational methodology of thetransmission controller according to the present invention;

FIGS. 13A-13C are flow charts of the shift select methodology of FIG. 12according to the present invention;

FIGS. 14A-D illustrate the shift schedule methodology according to thepresent invention; FIG. 14A is a flow chart of the shift schedulemethodology of FIG. 12; and FIGS. 14B-14D are shift schedule graphs;

FIGS. 15A-B illustrate the PSLOPE methodology according to the presentinvention; FIG. 15A is a flow chart of the PSLOPE methodology of FIGS.14; and FIG. 15B is a graph of the method used in FIG. 15A;

FIGS. 16A-D are flow charts of the shift methodology of FIG. 12according to the present invention; FIG. 16A is a flow chart of theupshift methodology; FIGS. 16B and 16C are flow charts of the downshiftmethodology; and FIG. 16D is a flow chart of the garage shiftmethodology.

TRANSMISSION CONTROL METHOD

Referring to FIG. 12, the logic or methodology of the transmissioncontroller 3010 is shown at 800. When the key of the vehicle is turnedon, power-up of the transmission controller 3010 occurs in bubble 802.Next, the transmission controller 3010 performs or enters a sevenmillisecond (7 ms.) main program or control loop. At the beginning ofthe main control loop, the methodology advances to block 804 calledshift select to "orchestrate" various methods used to determine theoperating mode or gear, i.e. first gear, the transmission 100 ispresently in and which gear the transmission 100 should be in next, andcomparing the two to each other to determine if a shift is required. Themethodology advances to bubble 806 to calculate the speed andacceleration of the turbine 128, output gear 534 and engine crankshaft114. The transmission controller 3010 receives input data from theturbine speed sensor 320 (turbine speed N_(t)), output speed sensor 546(output speed N_(o)) and engine speed sensor (not shown) (engine speedN_(e)) in circle 808. In bubble 80 g, the engine speed N_(e), turbinespeed N_(t) and output speed N_(o) are calculated from the input data.The methodology advances to bubble 810 called the shift schedule to bedescribed under section heading "SHIFT SCHEDULE METHOD". The shiftschedule bubble 810 reads or determined the shift lever position 606,PRNODDL, of the manual lever 578 by contact switch sensor (NS₁, NS₂)(See FIG. 4B) in circle 812. The shift schedule bubble 810 alsodetermines the throttle angle THRT ANGLE of the engine, to be describedunder section heading " THROTTLE ANGLE COMPUTATION AND FAILUREDETECTION", by an input of a potentiometer (not shown) connected to thethrottle (not shown) in circle 814. The shift schedule bubble 810further determines the engine temperature, to be described under sectionheading "PRESSURE SWITCH TEST AND TRANSMISSION TEMPERATURE DETERMINATIONMETHOD" in circle 816. The shift schedule bubble 810 uses the data itemssuch as output speed N_(o) in circle 815 (generated by bubble 806),PRNODDL (generated by circle 812) and throttle angle (generated bycircle 814) to determine the appropriate gear the transmission 100should be placed.

The methodology advances to bubble 818 which outputs the appropriatecommand signals to the solenoid-actuated valves 630, 632, 634 and 636and properly energizes or de-energizes them based on which gear thetransmission 100 is in, as determined by circle 812. The methodologyadvances to bubble 820 to execute diagnostic or monitoring routines. Indiagnostic bubble 820, the transmission controller 3010 determines ifthe proper pressure switches 646, 648 and 650, previously described, arepressurized by either looking for signals from a specific pressureswitch combination for the present in-gear condition of the transmission100 or from a specific pressure switch to a non-controlling clutchduring a pressure switch test to be described. The transmissioncontroller 3010 also determines if the wires in the control system arenot shorted or open by looking for a flyback voltage or EMF spike duringa solenoid continuity test to be described under section "SOLENOIDCONTINUITY TEST METHOD". The methodology then advances to diamond 822and determines whether a failure has occurred. If a failure hasoccurred, the methodology advances to block 824 in which thetransmission controller 3010 de-energizes the solenoid-actuated valves630, 632, 634 and 636 which assume their normal positions to allow thetransmission 100 to operate in second gear in the drive mode, i.e.limp-home mode previously described. If a failure has not occurred, themethodology advances to the shift select block 804. Based on thecalculated speeds and shift schedule output (SSOUTP), the methodologydetermines if a shift is required. This process is done every 7 ms.

Since the shift select block 804 compares the gear the transmission 100is presently in, to the SSOUTP, the methodology advances to diamond 826and determines if a shift or gear change is required. If a shift isrequired, the methodology advances to block 828 called the shift logicto be described herein. Otherwise, if a shift is not required, themethodology advances to diamond 830 and looks at the lock-up schedules,i.e. a plot of THRT ANGLE verses N_(t), etc., to determine if lock-up ofthe torque converter 110 is required. If lock-up is not required, themethodology returns to the beginning of the shift select block 804 againfor another 7 ms. loop. Otherwise, if lock-up is required, themethodology advances to diamond 832 and determines if the torqueconverter 110 is presently locked-up by looking for a flag that haspreviously been set during full lock-up of the torque converter 110. Ifthe torque converter 110 is presently locked-up, the methodology returnsto the shift select block 804. Otherwise, the methodology advances toblock 834 called partial lock-up logic or methodology, to describedunder section heading "TORQUE CONVERTER LOCK-UP METHOD", for the torqueconverter 110.

If a shift or gear change is needed or required, the shift logic block828 uses one of twelve unique shift programs or routines. The shiftroutines are 1-2, 2-3, 2-4, 3-4 (upshifts); 4-3, 4-2, 3-2, 3-1, 2-1,(downshifts); and N-1, R-N, N-R (garage shifts) to be described herein.The shift logic block 828 has to identify the proper shift logicroutine, and then execute it. The shift logic block 828 controls thesolenoid-actuated valves 630, 632, 634 and 636 to shift the transmission100 from its present gear to the next gear in a smooth manner.

After the shift logic block 828, the methodology advances to diamond 836and determines if lock-up of the torque converter 110 is required aspreviously described. If lock-up is required, the methodology advancesto diamond 838 and determines whether the torque converter 110 isalready locked-up as previously described. If the torque converter isnot already locked-up, the transmission controller 3010 executes thepartial lock-up block 834, to be described herein.

The partial lock-up block 834 is used to reduce slip of the torqueconverter 110. Slip equals N_(e) minus N_(t). The partial lock-up block834 instructs or causes the transmission 100 to fully lock, partiallylock or fully unlock the torque converter 110. If unlock is desired, thetransmission controller 3010 will hold the solenoid-actuated valve 636in the de-energized or normally vented mode to move the LU switch valve614 and allow fluid pressure to disengage the lock-up clutch 186. Ifpartial lock is desired, the transmission controller 3010 will reduceslip to a low or predetermined desired value, but not completelyeliminate it. The transmission controller 3010 calculates the slip byN_(e) minus N_(t) based on the input from the sensors previouslydescribed. The transmission controller 3010 compares this to apredetermined desired value of slip, e.g. 60 r.p.m., and thus,determines if the torque converter 110 is slipping too much or toolittle. If too much slip occurs, the transmission controller 3010 willincrease the duty cycle ("ON" time) of the low/reverse clutchsolenoid-actuated valve 636 and the LU switch valve 614, which willincrease the pressure differential across the lock-up clutch assembly186 and thus, decrease the slip. This technique is called "pulse-widthmodulation".

If full lock-up is desired, the transmission controller 3010 willgradually increase the fluid pressure to the lock-up clutch 186, addingmore "ON" cycle time to the solenoid-actuated valve 636 therebyincreasing the "ON" cycle time at the LU switch valve 614 until maximum,resulting in zero slip.

Returning to diamond 836, if the transmission controller 3010 determinesthat lock-up of the torque converter 110 is not required, themethodology advances to bubble 840 to execute diagnostic or monitoringroutines as previously described. Similarly, if the transmissioncontroller 3010 determines that the torque converter 110 is alreadylocked-up in diamond 838, the methodology advances to bubble 840 toexecute diagnostic or monitoring routines as previously described.Further, once the partial lock-up block 834 is completed, themethodology advances to bubble 840 to execute diagnostic or monitoringroutines as previously described.

From diagnostic bubble 840, the methodology advances to diamond 842 anddetermines whether a failure has occurred as previously described. If afailure has occurred, the methodology advances to block 844 and causesthe transmission 100 to default to or operate in second gear. Otherwise,if no failure occurs in diamond 842, the methodology advances to diamond846 and determines if the time period for the diagnostic loop hasexpired by any suitable method such as looking at a counter. If the timehas not expired, the methodology advances to bubble 840 to execute thediagnostic routines again until the time period has expired. If the timeperiod has expired, the methodology advances to bubble 848 to calculatespeeds N_(e), N_(t) and N_(o) as previously described. The methodologythen advances to bubble 850 to perform another shift schedule aspreviously described using PRNODDL circle 852, output speed N_(o) circle855, THRT ANGLE circle 854, and engine temperature circle 856.

To perform the shift in a smooth manner, the transmission controller3010 slips the clutches of the multi-clutch assembly 300. Thetransmission controller 3010 has to control the pressure on applyingclutches and releasing clutches in an orchestrated manner. To do this,the methodology advances from the shift schedule bubble 850 to bubble858 and determines the appropriate rate of acceleration, called the"desired acceleration" (alpha_(desired) or α*) to control the turbine128. The desired acceleration may be predetermined by an equation,point/slope interpolation or any other suitable method. The methodologyadvances to bubble 860 and calculates the present acceleration(alpha_(t) or α_(t)) of the turbine 128 based on turbine speed N_(t)which tells the transmission controller 3010 how quickly the shift ishappening. The transmission controller 3010 indirectly compares thevalue of desired acceleration with the calculated acceleration. This maybe accomplished by placing the above values into an equation to decidethe duty cycle for proportional control to be described. The methodologyadvances to bubble 862 to output the appropriate command signals toeither actuate and/or deactuate (turn logically either "ON" or "OFF")the solenoid-actuated valves 630, 632, 634 and 636 for the engaging(apply) or disengaging (release) of the clutches.

For upshifts, if the turbine 128 is decelerating too fast, thetransmission controller 3010 reduces the pressure on the applying clutchby either actuating and/or deactuating the solenoid-actuated valves 630,632, 634 and 636 in bubble 862. For downshifts, if the turbine 128 isaccelerating too rapidly, the transmission controller 3010 increases thepressure on the applying clutch by either actuating and/or deactuatingthe solenoid-actuated valves 630, 632, 634 and 636 in bubble 862. If theturbine assembly 128 is accelerating at the desired acceleration level,the solenoid-actuated valves 630, 632, 634 and 636 are either actuatedand/or deactuated to obtain the shift or gear change. At the end of 7ms. loop, the methodology advances to diamond 864. The transmissioncontroller 3010 tallies the ratios of N_(t) to N_(o) again to determineif the shift or gear change is complete. If N_(o) and N_(t) are atproper values, i.e. ratio×N_(o) =N_(t) for a predetermined time periodwhich is different for each shift, the transmission controller 3010determines that the shift or gear change is complete. The methodologyreturns to the beginning of the control loop to the shift select block804. If the shift or gear change is not complete, the methodologyreturns to the shift logic block 828 to repeat the method as previouslydescribed.

SHIFT SELECTION METHOD

The shift "select" routine or method in block 804 of FIG. 12 falls inthe main loop immediately after system start-up in bubble 802 of FIG.12. The shift schedule routine of bubble 810 is called before shiftselection analysis is performed. All other key variables such as outputspeed N_(o), turbine speed N_(t), acceleration, etc. are also updatedprior to shift selection analysis. The shift schedule routine of bubble810 determines the appropriate gear the transmission 100 of the vehicleshould be placed in (See FIG. 13B) as described subsequently herein.This information is conveyed by setting the bits of "shift scheduleoutput" (SSOUTP). The shift selection block 804 compares the gearrelated bits of the in-gear code (IGCODE) as defined by circle 812 andSSOUTP. If they are equal, no shift is required. In this case, themethodology will decode what gear the transmission 100 is in and willrevalidate the proper "clutch" and "solenoid" states (i.e. eitherlogically "ON" or "OFF") of the valves 630, 632, 634 and 636 FIGS.5A-L).

The shift selection method (FIG. 13B) has enormous complexity. In orderto minimize the size of the method to a manageable level and to deriveRAM and ROM efficacy, a technique using a shift "control table" isemployed. Each row of the shift control table has four bytes. The shiftcontrol table format is defined as follows:

    ______________________________________                                                         SHCODE IF    COMPLEMENT                                      MASK  IGCODE     IGCODE TRUE  SHCODE                                          ______________________________________                                        (1)   (2)        (3)          (4)                                             ______________________________________                                         The SHCODE is the "shift code", i.e. from first to second gear. IGCCDE is     the in-gear code, i.e. present operating gear of the transmission 100.     MASK is the eight bit binary code for the result of a logical operation.

As illustrated in Figure 13A, the shift select block 804 is generallyshown for a shift selection while the transmission 100 is operating "ingear", i.e. the transmission 100 is presently in first gear for example.After power-up in bubble 802 of FIG. 12, the methodology enters theshift select through bubble 866. The methodology advances to block 868and points to the beginning or start of the shift control table (firstrow), previously described, which is stored in memory. The methodologyadvances to block 870 and prepares a "select mask" (M) from which theIGCCDE and SSOUTP are "logically ANL-ed". The methodology advances toblock 872 and compares mask (M) with the first byte in the shift controltable row. The methodology advances to diamond 874 and determineswhether a matching row was found. If a matching row was found, themethodology advances to block 876 and points to the next row in theshift control table. The methodology then loops back to diamond 874previously described.

If a matching row was found at diamond 874, the methodology advances todiamond 876 and determines whether the present IGCODE equals the secondbyte of the shift control table row. If the present IGCODE equals thesecond byte, the methodology advances to block 878 and picks the thirdbyte containing the shift to be performed, i.e. first to second gear. Ifthe present IGCODE does not equal the second byte, the methodologyadvances to block 880 and picks the fourth byte containing the shift tobe performed. The methodology advances from blocks 878 and 880 to bubble882. At bubble 882, the methodology returns or goes to top of shift inshift logic block 828 of FIG. 12 to perform the shift just selected. Theshift select block 804 is shown schematically in FIG. 13B.

If the present shift is to be abandoned for a new shift, i.e. a shiftselection while the transmission 100 is presently performing a shift, aselection process called "change-mind" analysis is used as illustratedin FIG. 13C. During the shift loop, the methodology enters thechange-mind portion of the shift selection block 804 through bubble 884.The methodology then advances to diamond 886 and determines whether anew shift schedule is different from the present shift schedule bylooking at the shift schedule output (SSOUIP) which may be a codedregister. If not, the methodology advances to bubble 888 and determinesthat change-mind analysis is not allowed and continues the presentshift. If the new shift schedule (SSCUTP) is different from the presentshift schedule, the methodology advances to block 890 and vectors to theproper change-mind processing point based on a change mind table storedin memory which is similar to the shift control table. In other words,the methodology uses a vector table oriented method for analysis of each"present shift" and jumps to the proper process point. The methodologythen advances to block 892 and performs checks using key variables (i.e.speeds, throttle angle, speed ratios, SSOUTP, IGCCDE, etc.) at itsappropriate processing point. The methodology advances to diamond 894and determines whether change-mind conditions are valid by the oldSSOUTP not matching the new or recent SSOUTP. If the conditions are notvalid, the methodology advances to bubble 888 previously described tocontinue the present shift. If the change-mind conditions are valid, themethodology advances to bubble 896 and aborts the present shift andselects the new shift from the processing point.

SHIFT SCHEDULE METHOD

The shift schedule method determines the appropriate gear in which thetransmission 100 should be placed. The shift schedule method firstdetermines the present gear of the transmission 100 by the shift leverposition 606 of the manual lever 578 in circle 812 of FIG. 12. Based onthe shift lever position 606, the shift schedule method determines theappropriate gear in which the transmission 100 should be placed.

Referring to FIG. 14A, the bubble 810 of FIG. 12 for the shift schedulemethod is shown. The methodology enters from the shift select block 804through bubble 900 and advances to diamond 902. At diamond 902, themethodology determines whether the shift lever position (SLP) 606 of themanual lever 578 is park P or neutral N by reading a coded signal fromthe sensors NS₁ and NS₂ (FIG. 4B) to be described. If SLP 606 is park orneutral, the methodology advances to block 904 and sets the new output(SSOUTP) of the shift schedule (SS) to neutral. The methodology thenreturns or emits through bubble 906.

At diamond 902, if SLP 606 is not park or neutral, the methodologyadvances to diamond 908 and determines whether SLP 606 is reverse R bythe signal from the sensors NS₁ and NS₂. If SLP 606 is reverse, themethodology then advances to block 910 and sets shift schedule toreverse. The methodology then returns or emits through bubble 906.

At diamond 908, if SLP 606 is not reverse, the methodology advances toblock 912 concludes or determines that SLP 606 is equal to overdrive OD,drive D or low L. The methodology then advances to block 914 and selectstwo adjacent lines based on the present shift schedule and the shiftschedule graphs shown in FIGS. 14B through 14D for a SLP 606 ofoverdrive OD, drive D or low L. The methodology advances to block 916and scans these lines using a technique called "point slope" (PSLOPE),to be described under section heading "PSLOPE METHOD" (FIGS. 15A and15B) which is a linear interpolation technique (N_(o) on X-axis andthrottle angle on Y-axis). The methodology advances to diamond 918 anddetermines whether there is a new shift schedule to a coastdown shift,i.e. second to first gear from the SSOUTP (for a downshift) and throttleangle (for coast versus kick). If there is a new shift schedule to acoastdown shift, the methodology advances to block 920 and checks thegear ratios of the gear assembly 500 by performing speed calculations toavoid a "shock" from a power-plant reversal situation. A power-plantreversal situation or condition exists when the wheels of the vehicledrive the engine through the transmission during deceleration ratherthan the engine driving the transmission, in turn, driving the wheels.The methodology advances to diamond 922 and determines whether apower-plant reversal situation or condition exists. If a power-plantreversal condition exists, the methodology advances to block 924 anddoes not change the shift schedule. The methodology returns or exitsthrough bubble 926.

At diamond 918, if there is not a new shift schedule to a coastdownshift, the methodology advances to block 928. Also, if a power-plantreversal condition does not exist at diamond 922, the methodologyadvances to block 928. At block 928, the methodology allows for a newshift schedule. The methodology then advances to block 930 and checksfor diagnostic situations or conditions as previously described inconjunction with FIG. 12. The methodology advances to diamond 932 anddetermines whether a diagnostic situation or condition exists. If adiagnostic condition does not exist, the methodology advances to block934 and allows the shift schedule to proceed or be changed to the newshift schedule. If the diagnostic condition does exist, the methodologyadvances to block 936 and does not change the shift schedule. Themethodology advances from blocks 934 and 936 to bubble 938 and exits orreturns.

PSLOPE METHOD

Referring to FIGS. 15A and 15B, the "point slope" (PSLOPE) routine ofblock 916 of FIG. 14A is shown. The PSLOPE method determines thethrottle angle given output speed N_(o) by scanning the shift lines inFIGS. 14B through 14D stored as a table in the memory of thetransmission controller 3010. At the start of the PSLOPE routine inbubble 1000 of FIG. 15A, the methodology advances to block 1002 andtemporarily stores the value for X in the memory of the transmissioncontroller 3010. The methodology then advances to diamond 1004 anddetermines whether X is less than or equal to X_(o) (FIG. 15B) which isa point on the shift line. If X is less than or equal to X_(o), themethodology advances to block 1006 and gets or obtains the value forY_(o) and returns or emits through bubble 1008. If X is greater thanX_(o), the methodology advances to diamond 1010 and determines whether Xis less than X_(R). If X is less than X_(R), the methodology advances toblock 1012 and computes the slope between the points X_(R) and X_(R-1).The methodology then advances to block 1014 and computes Y based onY_(R) plus slope. The methodology then returns or emits through bubble1016.

At diamond 1010, if X is not less than X_(R), the methodology advancesto diamond 1018 and determines whether the method is at the end of atable of values for the shift schedule graphs (FIGS. 14B-D), i.e. Y_(o); Y_(o) ; X_(R) ; Y_(R) ; X_(n) ; Y_(n). If the method is not at the endof the table, the methodology advances to block 1020 and goes to thenext row of the table. The methodology then loops back to diamond 1010.

If the methodology is at the end of the table at diamond 1018, themethodology advances to block 1022 and concludes or determines that thevalue for X is not in the table but greater than X_(n) (FIG. 15B), andgets the Y_(n) value, i.e. the last value Y_(n) from the data tablebased on the value for X_(n). The methodology then returns or emitsthrough bubble 1016.

SHIFT LOGIC METHOD

The shift logic block 828 contains twelve unique shift programs. Theshift logic block 828 identifies the shift logic or routine to beexecuted. For example, if the transmission 100 is in first gear and theshift schedule output (SSOUTP) changes to call for second gear, theshift selection block 804 picks a SHCODE and shift logic block 828identifies and executes the SHCODE for first to second (1-2) logic.

Each of the twelve different shifts involves extensive calculations andlogical manipulations to determine the "ON" Or "OFF" states of thesolenoids of the solenoid-actuated valves 630, 632, 634 and 636 (FIGS.5A-L) for engaging (applying) or disengaging (releasing) of the clutchesfor the shifts. These shifts are organized into three sets of shifts asfollows: upshifts 1-2, 2-3, 3-4 and 2-4; downshifts 2-1, 3-1, 4-3, 4-2and 3-2; and garage shifts N-1, N-R and R-N.

The methodology consists of three major routines, one for each of theabove sets of shifts. To make this possible, a "Control Table" method isused. The key parametric entities are imbedded in a shift control tableas follows:

    ______________________________________                                        SHIFT CONTROL TABLE                                                           FORMAT               NUMBER OF BYTES                                          ______________________________________                                        RELEASE ELEMENT BIT  (1)                                                      APPLY ELEMENT BIT    (1)                                                      ADDR. OF VF (APPLY)  (1)                                                      ADDR. OF VF (REL.)   (1)                                                      NI GEAR (initiating ratio)                                                                         (2)                                                      NJ GEAR (destination ratio)                                                                        (2)                                                      DESTINATION ELEMENT MASK                                                                           (l)                                                      ______________________________________                                    

All calibration variables are segregated into a separate table called a"Volume Table" for example, as follows:

    ______________________________________                                        VOLUME TABLES                                                                 CLUTCH IDENTIFIER   ELEMENT                                                   ______________________________________                                        103                 QF CU. INCH/MS.                                           54                  QV CU. INCH/MS.                                           1802                C CU. INCHES                                              185l4               VA CU. INCHES                                             17                  SLOPE QF                                                  74                  SLOPE QV                                                  VFLRC               ADDR. OF "VF"                                             ______________________________________                                    

Thus, during product development, the key flow-rate and volumetricparameters can be efficiently and manageably altered. As a result, eachmajor shift routine (upshift, downshift or garage shift) can do one ofits many shifts just by getting the necessary fixed parameters from theshift control table and the calibration (volumetric, flow rates, etc.)data from the volume tables.

Accordingly, this shift logic method provides the following advantages:efficient management of ROM and RAM resources of the transmissioncontroller 3010; efficiency during product calibration cycle; and defectpreventiveness during development due to the segregation by upshifts,downshifts and garage shifts and by fixed versus calibration parameters.

Referring to FIG. 16A, for upshifts of the shift logic block 828 of FIG.12, the methodology enters the start or top of shift in the shift logicblock 828 through bubble 1100. The methodology advances to diamond 1102and determines whether the torque converter 110 is presently in thelock-up mode as previously described. If the torque converter 110 ispresently locked, the methodology advances to block 1104 and instructsthe transmission controller 3010 to unlock the torque converter 110 whenslip from the present gear toward the target gear begins, i.e. fromfirst to second gear. The methodology then advances to block 1106.

At diamond 1102, if the torque converter 110 is not in the lock-up mode,the methodology advances to block 1106. At block 1106, the transmissioncontroller 3010 computes variables, such as t_(f) (time remaining tonearly fill the apply clutch, t_(r) (time to nearly release), DC_(t)(torque phase duty cycle) etc., states/flags to be used in shift logicequations and intercepts/calculates variables used for "learning", to bedescribed under section heading "LEARN METHODOLOGY" at the end of theshift. The methodology advances to block 1108 and solves a predeterminedlogic equation for the apply element such as a clutch. The methodologythen advances to diamond 1110 and determines whether the solenoid forthe apply element or oncoming clutch should be logically "ON" based oncalculated speeds, throttle angle and SSOUTP.

It should be appreciated that the friction element (apply or release)such as a clutch is turned logically "ON or OFF" by either theenergization or de-energization of the solenoid-actuated valve. Itshould also be appreciated that "ON" or "OFF" can be either "applying orventing" of the function element.

If the apply clutch should be ON, the methodology advances to diamond1112 and determines whether the apply clutch is under duty cyclecontrol, i.e. solenoid-actuated valve to the clutch is cycled "ON" and"OFF", by looking for a flag previously set. If the apply clutch is notunder duty cycle control, the methodology advances to block 1114 andturns ON or applies the apply clutch by energizing or de-energizing thesolenoid of the respective solenoid-actuated valve. If the apply clutchis under duty cycle control, the methodology advances to block 1116 andstarts or continues the duty cycle.

At diamond 1110, if the apply clutch should not be ON, or applied themethodology advances to block 1118 and turns OFF or disengages the applyclutch. The methodology advances from blocks 1114, 1116 or 1118 to block1120 and solves a predetermined the release clutch or off-going clutchlogic equation. The methodology advances to diamond 1122 and determineswhether the release clutch or off-going clutch should be ON based oncalculated speeds, throttle angle and SSOUTP. If the release clutchshould not be ON, the methodology advances to block 1124 and turns OFFor disengages the release clutch. The methodology then returns or emitsthrough bubble 1126.

At diamond 1122, if the release clutch should be ON or applied, themethodology advances to diamond 1128 and determines whether the releaseclutch is under duty cycle control by looking for a flag as previouslydescribed. If the release clutch is not under duty cycle control, themethodology advances to block 1130 and turns ON or applies the releaseclutch. The methodology returns or emits through bubble 1126.

At diamond 1128, if the release clutch is under duty cycle control, themethodology advances to block 1132 and starts or continues the dutycycle. The methodology emits through bubble 1126.

Referring to FIGS. 16B and 16C, the downshift logic for the shift logicblock 828 of FIG. 12 is shown. The methodology enters through bubble1200. The methodology advances to diamond 1204 and determines whetherthe torque converter 110 is unlocked as previously described. If thetorque converter 110 is not unlocked, the methodology advances to block1206 and aborts partial or full lock-up operation. The methodologyadvances to block 1208.

At diamond 1204, if the torque converter 110 is unlocked, themethodology advances to block 1208. At block 1208, the transmissioncontroller 3010 computes variables and states of flags to be used insimilar shift logic equations of the upshift logic. The methodologyadvances to diamond 1210 and determines whether the present shift is adownshift to first gear by the SSOUTP. If the present shift is adownshift to first gear, the methodology advances to diamond 1212 anddetermines whether the solenoid switch valve 610 has moved to the lowgear position (See FIG. 5E). The position of the solenoid switch valve610 is determined by checking pressure switch data from the pressureswitches 646, 648 and 650 within a predetermined time period. If thesolenoid switch valve 610 has moved to the low gear position, themethodology advances to diamond 1214 and determines whether the solenoidswitch valve 610 has moved back to the high gear or lock-up position(See FIG. 5F). If the solenoid switch valve 610 has moved back to thehigh gear position, the methodology returns or emits through bubble1216.

At diamond 1212, if the solenoid switch valve 610 has not moved to thelow gear position, the methodology advances to block 1218 and executessolenoid switch valve control logic (energizing and de-energizing thesolenoid-actuated valves 634 and 636), previously described, to move thesolenoid switch valve 610 to the low gear position. The methodology thenadvances to block 1220.

At diamond 1214, if the solenoid switch valve 610 has not moved back tothe high gear position, the methodology advances to block 1220. Atdiamond 1210, if the present shift is not a downshift to first gear, themethodology advances to block 1220. At block 1220, the transmissioncontroller 3010 solves the release clutch shift logic equation. Themethodology advances to diamond 1222 and determines whether the releaseclutch should be turned ON or applied as previously described. If therelease clutch should not be turned ON, the methodology advances toblock 1224 and turns OFF or disengages the release clutch.

At diamond 1222, if the release clutch should be turned ON, themethodology advances to diamond 1226 and determines whether the releaseclutch is in the duty cycle made as previously described. If the releaseclutch is not in the duty cycle mode, the methodology advances to block1228 and turns ON or applies the release clutch. If the release clutchis in the duty cycle mode, the methodology advances to block 1230 andstarts or continues the release clutch duty cycle. The methodologyadvances from blocks 1224, 1228 and 1230 to diamond 1232.

At diamond 1232, the transmission controller 3010 determines whether thepresent shift is a downshift to first gear as previously described. Ifthe present shift is a downshift to first gear, the methodology advancesto diamond 1234 and determines whether the solenoid switch valve 610 hasroved to the low gear position as previously described. If the solenoidswitch valve 610 has not moved to the low gear position, the methodologyemits or returns through bubble 1236. If the solenoid switch valve 610has moved to the low gear position, the methodology advances to block1238. If the present shift is not a downshift to first gear at block1232, the methodology advances to block 1238.

At block 1238, the transmission controller 3010 solves the shift logicequation for the apply clutch and intercepts/calculates the necessarydata for "learning" at the end of the shift to be describedsubsequently. The methodology advances to diamond 1240 and determineswhether to turn ON the apply clutch.

If the transmission controller 3010 determines not to turn ON the applyclutch, the methodology advances to block 1242 and turns OFF ordisengages the apply clutch. If the transmission controller 3010determines to turn ON the apply clutch, the methodology advances todiamond 1244 and determines whether the apply clutch is in the dutycycle mode as previously described. If the apply clutch is not in theduty cycle mode, the methodology advances to block 1246 and turns ON theapply clutch. If the apply clutch is in the duty cycle mode, themethodology advances to block 1248 and starts or continues the applyclutch duty cycle. The methodology advances from blocks 1242, 1246 and248 to block 1250.

At block 1250, the transmission controller 3010 solves a non-controllingclutch shift logic equation similar to the controlling shift logicequations needed for the shift to occur as previously described. Aclutch other than one needed to make the shift or gear change is calledthe non-controlling clutch. This clutch is cycled ON and OFF by theappropriate solenoid-actuated valve to improve shift quality. Themethodology advances from block 1250 to diamond 1252 and determineswhether to turn ON or apply the non-controlling clutch based oncalculated speeds, throttle angle and SSOUTP. If the transmissioncontroller 3010 determines not to turn ON the non-controlling clutch,the methodology advances to block 1254 and turns OFF or disengages thenon-controlling clutch. If the transmission controller 3010 determinesto turn ON the non-controlling clutch, the methodology advances to block256 and turns ON the non-controlling clutch. The methodology returns oremits from blocks 1256 and 1256 through bubble 1258.

Referring to FIG. 16C, the garage shift methodology for the shift logicblock 828 of FIG. 12 is shown. The methodology enters the shift logicblock 828 through bubble 1300. The methodology advances to block 1302and turns the non-controlling clutches either ON or OFF, i.e. engagesdisengages the clutches not needed to perform the garage shifts. Themethodology advances to diamond 1304 and determines whether the presentshift is a garage shift to first gear by looking at SHCODE. If thepresent shift is a garage shift to first gear, the methodology advancesto diamond 1306 and determines whether the solenoid switch valve 610 hasmoved to the first gear position (FIG. 5E) as previously described. Ifthe solenoid switch valve 610 has not moved to the first gear position,the methodology advances to block 1308 and performs solenoid switchvalve control logic as previously described. The methodology then emitsor returns through bubble 1310.

At diamond 1304, if the shift is not a garage shift to first gear, themethodology advances to block 1312. At diamond 1306, if the solenoidswitch valve 610 has moved to the first gear position, the methodologyadvances to block 1312. At block 1312, the transmission controller 3010computes variables and states of flags to be used in a controlling shiftlogic equation similar to those in the upshift logic. The methodologyadvances to block 1314 and solves the controlling clutch shift logicequation. The methodology advances to diamond 1316 and determineswhether to turn ON the controlling clutch as previously described. Ifthe controlling clutch is not to be turned ON, the methodology advancesto block 1318 and turns OFF the controlling clutch. If the controllingclutch is to be turned ON, the methodology advances to diamond 1320 anddetermines whether the controlling clutch is under duty cycle control aspreviously described. If the controlling clutch is not under duty cyclecontrol, the methodology advances to block 1322 and turns ON thecontrolling clutch. If the controlling clutch is under duty cyclecontrol, the methodology advances to block 1324 and starts or continuesthe apply clutch duty cycle. The methodology returns or emits fromblocks 1318, 1322 and 1324 through bubble 1326.

ACCELERATION CALCULATION

The purpose of the acceleration calculation is to control transmissionoperation during a shift or gear change. The acceleration calculationdetermines the actual acceleration of the turbine 128. This is a majorfactor in determining overall response of the control system.

Referring to FIG. 12, the calculated speed bubble 806 is illustrated. Atmost speeds, the speed calculation is made by counting the number ofteeth 319, 544 during a predetermined cycle and dividing that toothcount by the actual time elapsed between the first and last tooth. Timeis measured by counting clock cycles in the transmission controller3010. The tooth center lines are determined by reading a magnetic sensor320, 546 for the sixty-tooth input clutch retainer hub 312 for turbinespeed N_(t), and for the twenty-four-tooth second planet carrier 524 foroutput speed N_(o), respectively. At lower speeds, when no tooth passesduring the 7 millisecond (ms.) cycle, the update rate must be extendedto more than one predetermined cycle, i.e. 14 ms., 21 ms., etc., toprovide data down to the minimum speed needed.

Referring to FIG. 12, the calculated acceleration bubble 860 isillustrated. Acceleration is calculated by dividing the speed changebetween the last two measurements by the average of the two elapsedtimes.

    N.sub.t =n(i)/T(i) ##EQU1##

N_(t) =calculated turbine r.p.m.

N_(o) =calculated output r.p.m.

alpha_(t) α_(t) =calculated turbine acceleration, r.p.m./sec.

n(i)=no. of teeth in latest count

n(i-1)=no. of teeth in previous count

T(i)=time required for n(i) teeth, seconds

T(i-1)=time required for n(i-1) teeth, etc.

For turbine speed N_(t) and acceleration alpha_(t), the calculationrange is from 40 to 6500 r.p.m. Acceleration must be calculated as soonas practical after reading turbine speed data because any time use slowsthe overall system response. For output speed N_(o), the calculationrange is from 40 to 6000 r.p.m. Due to problems with low speed dataintegrity, the maximum change for any update must be limited toplus/minus 30 r.p.m. when the previous output speed is less than 300r.p.m.

At low speeds (below about 1500 r.p.m.), an alternate method ofcalculating turbine acceleration is used. At higher speeds, however, therun-out inherent in the turbine speed wheel would generate a largefirst-order alternating acceleration term if this approach were used,thus interfering with good control.

To overcome this, a first-order filter is employed, which calculatesacceleration over an entire revolution. Speed is calculated based oneach quarter-revolution, the fourth previous speed (one revolutionbefore) is subtracted, and the difference is divided by the time for theone revolution. Because this acceleration calculation is more delayed,particularly at low speed, anticipation is necessary in order to achieveacceptable frequency response.

The following table defines the speed and acceleration calculations asfunctions of Ω, the number of quarter revolutions times. Ω=0 representslow speed operation. As the turbine accelerates, when 11 or more teeth(out of 60) pass in 7 ms., the switch to quarter revolution is initiatedand Ω begins to increment. After the fifth quarter revolution, onerevolution acceleration can be calculated; and after two more quarterrevolutions anticipation is effected. Low speed operation is resumedwhen more than 11.3 ms. is required for a quarter revolution.

    ______________________________________                                        Ω                                                                              N.sub.t    α(i)       α.sub.t                              ______________________________________                                        0      n(i)/T(i)                                                                                 ##STR1##        α(i)                                 1      15/T(i)    "                "                                          2-4    "                                                                                         ##STR2##        "                                          5-6    "                                                                                         ##STR3##        "                                          7      "          "                α.sub.a                              ______________________________________                                    

where:

n(i)=no. of teeth in latest count (assuming 60-tooth wheel)

n(i-1)=no. of teeth in previous count

T(i)=time required for n(i) teeth, seconds

T(i-1)=time required for n(i-1) teeth, etc.

N_(t) =calculated turbine r.p.m.

.sub.α (i)=calculated turbine acceleration, r.p.m./sec.

.sub.αt =turbine acceleration term for use in shift logic

.sub.αa =anticipated turbine acceleration, where

.sub.αa =(1/4)*[(36-3B)*.sub.α (i)-(52-5B)*.sub.α (i-1)+(20-2B)*₆₀(i-2)]

.sub.α (i-1)=calculated accel. for previous quarter revolution, etc.

B=INT [N_(t) /512]; limit B≦ 9

The present invention has been described in an illustrative manner. Itis to be understood that the terminology which has been used is intendedto be in the nature of words of description rather than of limitation.

Obviously, many modifications and variations are possible in light ofthe above teachings. Therefore, the subject invention may be practicedotherwise than as specifically described.

What is claimed is:
 1. In a vehicle having an engine and a transmissionincluding an input member, a torque converter for transmitting torquebetween a crankshaft of the engine and the input member of thetransmission, the torque converter having a turbine connected to theinput member, an output member, a gear assembly for changing the ratioof torque between the input member and the output member, a plurality offriction elements for shifting the gear assembly, a plurality of sensorsfor providing signals indicative of measurement data for predeterminedconditions, a controller having memory for processing and storing thesignals and predetermined values and for providing output signals, amethod of determining the acceleration of a turbine in a vehicletransmission to control the operation of the transmission, said methodcomprising the steps of:during each predetermined time period, sensingthe number of tooth centerlines which pass the speed sensor; sensing atime period between the passing of the last tooth and the end of thepredetermined time period; taking the predetermined period time,subtracting the sensed time period and adding the sensed time periodfrom the previous period to obtain the exact time sensed for the fullpassage of the teeth whose centerlines were sensed during thepredetermined time period; calculating speed by dividing the sensednumber of teeth by the exact time of passage of the same teeth; if notooth centerline should pass in the predetermined time period, continueto sense for tooth centerlines and increase the time used in the speedcalculation by the predetermined period time; repeat this as required tocalculate speeds down to the desired level each time subtracting thesensed time period for the latest passing centerline from theaccumulated period times and adding the sensed time period from the lastprevious period which observed a passing centerline to obtain the exacttime of passage of all of the counted tooth centerlines; calculating theacceleration of the turbine by the difference between the calculatedinput speed and the previous input speed and dividing one-half of thesum of the exact time of passage used in the latest speed calculationand the previous calculation; and controlling the application of thefriction elements in the transmission using the calculated acceleration.2. In a vehicle having an engine and a transmission including an inputmember, a torque converter for transmitting torque between a crankshaftof the engine and the input member of the transmission, the torqueconverter having a turbine connected to the input member, an outputmember, a gear assembly for changing the ratio of torque between theinput member and the output member, a plurality of friction elements forshifting the gear assembly, a plurality of sensors for providing signalsindicative of measurement data for predetermined conditions, acontroller having memory for processing and storing the signals andpredetermined values and for providing output signals, a method ofdetermining the acceleration of a turbine in a vehicle transmission tocontrol the operation of the transmission, said method comprising thesteps of:calculating the speed of the turbine by sensing the number ofteeth of the turbine passing a sensor during a predetermined time periodand dividing the sensed number of teeth by the predetermined timeperiod; calculating the output speed of the transmission by sensing thenumber of teeth on an output member of the transmission passing a sensorduring a predetermined time period and dividing the sensed number ofteeth by the predetermined time period; calculating the acceleration ofthe turbine by the difference between the present calculated turbinespeed and a previous calculated turbine speed and dividing by apredetermined constant multiplying the difference between the timerequired for a predetermined number of teeth and predetermined number ofteeth minus one; and controlling the application of the frictionelements in the transmission using the calculated acceleration.
 3. In avehicle having an engine and a transmission including an input member, atorque converter for transmitting torque between a crankshaft of theengine and the input member of the transmission, the torque converterhaving a turbine connected to the input member, an output member, a gearassembly for changing the ratio of torque between the input member andthe output member, a plurality of friction elements for shifting thegear assembly, a plurality of sensors for providing signals indicativeof measurement data for predetermined conditions, a controller havingmember for processing and storing the signals and predetermined valuesand for providing output signals, a method of determining theacceleration of a turbine in a vehicle transmission to control theoperation of the transmission, said method comprising the stepsof:sensing the number of teeth of the turbine passing a sensor during aquarter-revolution of the turbine; calculating the speed of the turbinebased on the sensed number of teeth during a quarter-revolution o theturbine; subtracting the fourth-previous calculated speed of the turbinefrom the calculated speed of the turbine; calculating the accelerationof the turbine by dividing the difference between the present calculatedspeed and the fourth-previous calculated speed by a predetermined timeperiod for one revolution of the turbine; and controlling theapplication of the friction elements in the transmission using thecalculated acceleration.